Description

185001089

Aim:
Procedure:
• Mount masm folder to a drive on DOSBOX.
• Navigate to mounted drive using ‘dir’ .
• Save 8086 program with the extension ‘.asm’ in the same folder using the command ‘edit’.
• Assemble the .asm file using the command ‘masm filename.asm’.
• Link the assmebled .obj file using the command ‘link filename.obj’.
• Debug the executable file .exe with the ‘debug filename.exe’ command.
i. U: To view the un-assembled code.
ii. D: Used as ‘D segment:offset’ to see the content of memory locations starting from segment:offset address. iii. E: To change the values in memory. iv. G: Execute the program using command.
v. Q exits from the debug session.
Algorithm:
∗ START: Move the starting address of data segment to AX register and move the data from AX register to DS register.
∗ Move 2ah to AH register.
∗ Calling int 21H with 2a in AH register will return year in CX register, month in DH register, day in DL register and day of the week in AL register.
∗ Move the offset of the variable DAY in SI register.
∗ Move the contents stored in DL register to the location in SI register.
∗ Move the offset of the variable MONTH in SI register.
∗ Move the contents stored in DH register to the location in SI register.
∗ Move the offset of the variable YEAR in SI register.
∗ Move the contents stored in CX register to the location in SI register.
2. System Time
∗ START: Move the starting address of data segment to AX register and move the data from AX register to DS register.
∗ Move 2ch to AH register.
∗ Calling int 21H with 2c in AH register will return hour in CH register, minute in CL register and second in DH register.
∗ Move the offset of the variable HOUR in SI register.
∗ Move the contents stored in CH register to the location in SI register.
∗ Move the offset of the variable MINUTE in SI register.
∗ Move the contents stored in CL register to the location in SI register.
∗ Move the offset of the variable SECOND in SI register.
∗ Move the contents stored in DH register to the location in SI register.

Program:
Program Comments
start: MOV AX,data Move data segment address contents to AX register
MOV ds,AX Move data in AX register to DS register
MOV AH, 2AH AH is loaded with 2Ah
MOV SI, OFFSET DAY Load offset of DAY into SI
MOV [SI], DL Load the day in DL into DAY
MOV SI, OFFSET MONTH Load offset of MONTH into [SI]
MOV [SI], DH Load month in DH into [SI]
MOV SI, OFFSET YEAR Load offset of YEAR into SI
MOV [SI], CX Load year in CX into [SI]
MOV ah,4ch
INT 21h Request interrupt routine
Unassembled Code:

Input and Output:

2. System Time
Program Comments
start: MOV AX,data Move data segment address contents to AX register
MOV ds,AX Move data in AX register to DS register
MOV AH, 2CH AH is loaded with 2Ch
INT 21H INT 21h when AH = 2Ch – get system time
MOV SI, OFFSET HOUR Load offset of HOUR into SI
MOV [SI], DL Load the hour in DL into HOUR
MOV SI, OFFSET MINUTE Load offset of MINUTE into [SI]
MOV [SI], DH Load minute in DH into [SI]
MOV SI, OFFSET SECOND Load offset of SECOND into SI
MOV [SI], CX Load second in CX into [SI]
MOV ah,4ch
INT 21h Request interrupt routine
Unassembled Code:

Input and Output:

Result: